Sheet gripper means for presses



Jan. 6, 1959 F.- LAUFER SHEET GRIPPER-MEANS FOR PRESSES Filed uly 11, 1957 I &\\\\\\\\\\\\\\ 2 Fig.2.

United States Patent SHEET GRIPPER MEANS FOR PRESSES Frdric Laufer, Prilly, Switzerland, assignor to J. Bobst and Son S. A., Prilly, near Lausanne, Switzerland, a corporation of Switzerland Application July 11, 1957, Serial No. 671,335 Claims priority, application Switzerland July 18, 1956 4 Claims. (Cl. 164-48) This invention relates to presses for working sheet material.

One known method of conveying sheet material such as paper or cardboard in presses is by means of gripper bars which insert the sheets between tool bearing platens and then remove the worked sheets and so forth.

Known gripper bars, which have a flat profile, support on one of their faces grippers which by way of example are in the shape of flexible strips which as a rule are not longer than the width of the associated bar.

As a result, the sheets are held between the said grippers and the face of the bar supporting the latter, the bar constituting a jaw common to all the grippers. The margin along the edge of each sheet resting on the bar cannot be worked, as the press tools can only operate on the portion of the sheet extending beyond the gripper bar.

Frequently an appreciable economy of material could be effected if cutting, for example, were to continue as far as the very edge of the sheet. This can be permitted in a manner which would in no way prevent a clamping of the sheet from being effected at neighboring points or zones.

In order to achieve this advantage a press which is provided in accordance with this invention has gripper bars which are notched between the grippers to a depth at least equal to the overlap of the sheets on the face of the bar, means being provided to enable the tools to be worked inside of one or more of these notches.

The annexed drawing shows an embodiment of the invention given by way of example:

Fig. l is a cross-sectional view of a bar showing a gripper holding a sheet being worked between the two tools of a press;

Fig. 2 is a similar sectional view illustrating one of the notches in the bar as seen between two clamping devices; and

Fig. 3 is a perspective view of the elements shown in the foregoing figures.

A sheet 1, which by way of example is cardboard, is punched between the tools shown in the drawing, said toolsbeing supported respectively in the upper platen 2 and on the lower platen which is covered by a plate 3. Cutters 4 and 5 are provided for the upper tool and, on plate 3, a sheet 6 is utilized for the make-ready for the lower tool.

During the cutting operation, the sheet 1 is held in position between the tools by means of the gripper bar 7, the upper face of the latter and the strips 8 forming the individual clamping jaws.

The pistons 9, together with push-rods or cams, are

2 used to open the grippers when they are to be prepared to grip a blank sheet or to release a sheet after it has been worked.

As can be seen, the bar 7 is notched at 10 between the grippers 8 whereby the jaws formed by the grippers constitute protrusions. The depth of the notches is barely larger than the width of the marginal strip of the sheet 1 seized by the grippers and resting on the bar.

Normally a sheet can be cut only in that portion which rests on the plate 3 and on the thin plate 6, and not in the marginal strip which lies within the grippers. That is to say normal cutting is only efiected by way of example at 5' (Fig. 3) by means of the cutter 5 (Figs. 1 and 2), but not at 4' as the latter falls on the associated bar.

In the example illustrated in the drawings, due to the notches 10, cutting can also be carried out at 4'. In

this way it is possible, for instance, to remove a section of the sheet border which is to be used as an assembling or gluing strip in a box which has been shaped.

The cutting 4 can be efiected only if the cutter 4 has a counterpart. The lower tool or plate 3, however, is recessed at 11 to permit the passage of the bar 7 and thus has no element for insertion into the notches 10.

On account of this, auxiliary blocks 12 are provided to be engaged in the notches, with their upper face flush with the thin plate 6. These blocks then provide tool 4, for instance, with the necessary counterpart.

These blocks are fitted only where they are required and can be fixed in various ways.

The example shown in the drawing shows that the plate 3 presents an L-shaped edge in which the blocks fit. Hence, they can either be screwed laterally against the plate, by means of screws with their axes parallel to the plane of the plate, or screwed on from below with vertical screws. In both cases, the height of the blocks can be adjusted accurately by means of wedges.

It would also be possible to provide the lower tool with a notched profile.

Finally, it is to be noted that the terms lower and upper have only a relative value since the whole system can be rotated through an angle of What I claim is:

1. Apparatus for processing a sheet comprising a support adapted to support the sheet for the performance of work on the latter, gripper means for gripping the sheet at spaced portions of a margin of said sheet, and auxiliary means on the support and efiectively constituting a part thereof and defining at least one opening to accommodate said gripper means thereby to provide support for the margin of the sheet other than at said portions.

2. Apparatus as claimed in claim 1 wherein the gripper means comprises a bar, and at least one resilient I member on and extending transversely of the bar and forming a gripper jaw therewith, said bar defining notches adjacent said jaw whereby the latter constitutes a protrusion, said auxiliary means accommodating said jaw.

3. Apparatus as claimed in claim 2 wherein the auxiliary means comprises at least one block detachably mounted on said support.

4. Apparatus as claimed in claim 2 wherein the margin has a determinable depth, said notches being deeper than said depth.

No references cited. 

